不同干燥方式对香露兜叶粉理化特性和功能性物质的影响

Effects of Different Drying Methods on Physicochemical Properties and Functional Material of Pandanus amaryllifolius Powder

以新鲜香露兜叶为原料,采用自然干燥(natural drying,ND)、热风干燥(hot air drying,HAD)、真空冷冻干燥(vacuum freeze drying,FD)、微波干燥(microwave drying,MWD)4种干燥方式对香露兜叶进行干燥加工,并分析不同干燥方式获得香露兜叶粉的理化特性和功能性物质。结果表明:不同干燥方式对香露兜叶粉的复水比、堆积密度、休止角、滑动角、粒径分布均有明显影响;MWD、FD很好地保持香露兜叶原有的a^(*)值,与鲜叶的a^(*)值相比无显著差异;FD香露兜叶粉的表面微观结构最为平滑和完整,不同干燥处理后香露兜叶粉的表面微观结构存在明显差异;FD、MWD香露兜叶粉的总酚含量较高。总体上来说,不同干燥方式处理的香露兜叶粉在色泽、粉质特性及总酚含量方面整体上均存在明显差异。FD在色泽、粉质特性、表面微观结构及总酚含量方面均优于其他干燥方式,FD是最适宜用于香露兜叶粉的干燥加工技术。而FD干燥时间较长、耗能高,MWD香露兜叶粉的色泽、总酚等指标优于ND和HAD,也可将MWD作为香露兜叶粉干燥加工中一种较好的备选干燥方式。

This study used fresh Pandanus amaryllifolius leaves as raw materials,and dried P.amaryllifolius leaves by four drying methods:natural drying(ND),hot air drying(HAD),vacuum freeze drying(FD),and microwave drying(MWD).The physicochemical properties and functional material of P.amaryllifolius leaves obtained by different drying methods were studied and analyzed.The results showed that the rehydration ratio,bulk density,angle of repose,slip angle,and particle size distribution of P.amaryllifolius powder by the different drying methods were significantly different.Specifically,MWD and FD effectively maintained the original a^(*)value of P.amaryllifolius leaves,and there was no significant difference compared to the a^(*)value of fresh leaves.The surface microstructure of FD samples was the smoothest and most intact,and there were significant differences in the surface microstructure of FD samples across different drying treatments.The total phenolic content of FD and MWD P.amaryllifolius powder was higher.In general,there were significant differences in color,powder properties,and total phenolic content of P.amaryllifolius powder treated with different drying methods.FD is superior to other drying methods in terms of color,powder properties,surface microstructure,and total phenolic content.FD was the most suitable drying technology for P.amaryllifolius powder,despite its longer drying time and higher energy consumption.The results of this study showed that the color,total phenols,and other indicators of MWD P.amaryllifolius powder were favorable than ND and HAD treatment,and MWD could also be used as a viable alternative drying method in the drying process of P.amaryllifolius powder.